JP2015183584A - general-purpose engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a general-purpose engine capable of pushing back storage oil in a crank case, even if flowing into a dynamic valve chamber in a state in which an inclined cylinder block is further inclined, to the crank case.SOLUTION: In a general-purpose engine including: a cylinder block 3 extending obliquely from one side of a crank case 2; and a cylinder head joined to an end surface of this cylinder block 3 via a gasket 4, a one-way valve V is provided in an upper oil passage 20 for allowing a flow of a fluid from the crank case 13 to a dynamic valve chamber 14 but preventing a reverse flow of the fluid, and lubricating oil 23 flowing into the dynamic valve chamber 14 is pushed back to a crank chamber 13 by a positive pressure transmitted from the crank chamber 13 to the dynamic valve chamber 14 if the lubricating oil 23 stored in the crank chamber 13 flows into the dynamic valve chamber 14 through a lower oil passage 21 by inclination of an engine E so that the inclined cylinder block 3 is further inclined.

Description

  The present invention relates to a general-purpose engine used for powering various working machines such as lawn mowers, in particular, a crankcase having a mounting flange at the bottom, a cylinder block extending obliquely from one side of the crankcase, and the cylinder block And a cylinder head joined to the end face of the engine through a gasket. The crankcase in the crankcase has an oil splash that scatters the stored lubricating oil in the crankcase and generates oil splashes for lubricating parts of the engine. General-purpose engine provided with generating means, and provided with an upper oil passage and a lower oil passage communicating with the crank chamber and the valve operating chamber in the cylinder head at the upper and lower portions of the cylinder block and cylinder head, respectively. Regarding improvements.

  Such a general-purpose engine is already known as disclosed in Patent Document 1, for example.

Japanese Utility Model Publication No. 62-15451

  In this type of general-purpose engine, the tilted cylinder block may be further tilted depending on the use condition of the work implement. In this case, a large amount of stored oil in the crank chamber passes through the lower oil passage to the valve operating chamber. By flowing in, the amount of oil stored in the crankcase is greatly reduced, and the generation of oil droplets by the oil droplet generation means becomes insufficient, which may hinder the lubrication of each part of the engine.

  The present invention has been made in view of such circumstances, and even if the inclined cylinder block is further inclined, even if the stored oil in the crank chamber flows into the valve operating chamber through the lower oil passage, this is immediately applied to the crank chamber. It is an object of the present invention to provide the general-purpose engine which is pushed back to ensure that the amount of oil stored in the crank chamber is secured and does not hinder the lubrication of each part of the engine.

  In order to achieve the above object, the present invention is joined to a crankcase having a mounting flange at the bottom, a cylinder block extending inclined from one side of the crankcase, and an end surface of the cylinder block via a gasket. A cylinder head, and a crank chamber in the crankcase is provided with oil splash generating means for splashing the stored lubricating oil in the crank chamber to generate oil splash for lubricating each part of the engine. In the general-purpose engine provided with an upper oil passage and a lower oil passage communicating with the crank chamber and the valve operating chamber in the cylinder head on the upper side and the lower side, respectively, A one-way valve that allows the flow of fluid from the valve side to the valve chamber side but prevents the reverse flow, When the engine is tilted so that the dabloc is further tilted, when the stored lubricating oil in the crank chamber flows into the valve chamber through the lower oil passage, the valve chamber is connected to the valve chamber via the one-way valve. The first feature is that the oil flowing into the valve operating chamber is pushed back to the crank chamber through the lower oil passage by the positive pressure transmitted to the valve. The oil splash generating means corresponds to an oil dipper 24 in an embodiment of the present invention described later.

  According to the present invention, in addition to the first feature, the upper oil passage is divided into an upstream passage on the crank chamber side and a downstream passage on the valve train chamber side by a gasket interposed between the cylinder block and the cylinder head. The gasket is provided with a valve mounting hole and a plurality of through holes communicating with the upstream passage and the downstream passage so as to surround the valve mounting hole, and the one-way valve is provided in the downstream passage. An elastic umbrella portion that sits on the upper surface of the gasket that faces and covers the through hole group, a valve body that protrudes from a boss portion of the elastic umbrella portion and penetrates the valve mounting hole, and is fitted into the flange portion In this case, the second feature is that it is constituted by a holding member that clamps the gasket in cooperation with the boss portion by being fixed.

  Furthermore, in addition to the second feature, the present invention forms the collar portion with a large diameter so that the outer peripheral surface thereof does not contact the inner peripheral surface of the valve mounting hole, A third feature is that a plurality of positioning claws are provided to engage with the through holes and hold the flanges in concentric positions with the valve mounting holes.

  Furthermore, in addition to the second or third feature, the present invention includes a first shaft portion that extends from the boss portion and fits into the fitting hole of the holding member, and the first shaft portion. And a second shaft portion having a diameter smaller than that of the first shaft portion. The enormous portion engages with the back surface of the holding member to place the holding member on the first shaft portion. The fourth feature is that the first shaft portion is formed to have a diameter larger than that of the first shaft portion.

  According to the first aspect of the present invention, the engine is forced to take a posture in which the inclined cylinder block is further inclined according to the use state of the work machine, and the oil in the crank chamber is driven through the lower oil passage. Even if a large amount flows into the chamber, due to the operation of the engine, the positive pressure of the pulsating pressure generated in the crank chamber passes through the upper oil passage in the upper oil passage due to the action of the one-way valve. By being transmitted, the pressure in the valve chamber increases, and the oil flowing into the valve chamber can be pushed back to the crank chamber through the lower oil passage. Therefore, it is possible to prevent a decrease in the amount of oil stored in the crank chamber, to always generate oil splashes by the oil splash generating means, and to ensure a good lubrication state of each part of the engine.

  According to the second feature of the present invention, a one-way valve can be easily attached using a gasket, and this one-way valve can be employed without significant modification to a conventional engine. The improvement cost can be kept low.

  According to the third feature of the present invention, the flange portion of the valve element is placed at a certain distance from the inner peripheral surface of the valve mounting hole over the entire circumference thereof, so that the flange portion has a wall thickness. Damage due to contact with the sharp inner periphery of the valve mounting hole of the thin gasket can be prevented and its durability can be maintained. In addition, since the positioning claw is engaged using a through hole that allows a positive pressure to pass through, it is not necessary to provide a special positioning hole in the gasket, which can contribute to simplification of the structure.

  According to the 4th characteristic of this invention, the assembly property of a one-way valve can be made favorable.

The front view of the general purpose engine which concerns on embodiment of this invention. The longitudinal cross-sectional front view of the said general purpose engine. FIG. 3 is an enlarged sectional view taken along line 3-3 in FIG. 2. FIG. 4 is an enlarged sectional view taken along line 4-4 of FIG.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 and 2, the general-purpose engine E includes a crankcase 2 having a mounting flange 1 at the bottom, a cylinder block 3 extending obliquely from one side of the crankcase 2, and a gasket 4 on an end surface of the cylinder block 3. The fuel tank T is attached to the upper part of the crankcase 2, and the air cleaner A is attached to the upper part of the cylinder block 3. The installation flange 1 is installed on a working machine powered by the general-purpose engine E.

  A crankshaft 7 is disposed in a crank chamber 13 in the crankcase 2, and the crankshaft 7 is connected to a piston 8 fitted in a cylinder bore 3 a of the cylinder block 3 via a connecting rod 9. The cylinder head 5 has a combustion chamber 10 connected to the cylinder bore 3a, an intake port 11i and an exhaust port (not shown) that open to the combustion chamber 10, and opens and closes the intake port 11i and the exhaust port, respectively. An intake valve 12i and an exhaust valve (not shown) are provided. In the valve operating chamber 14 in the cylinder head 5, an intake rocker arm 18i and an exhaust rocker arm (not shown) of the valve operating device 15 for opening and closing the intake valve 12i and the exhaust valve are disposed. The intake rocker arm 18i and the exhaust rocker arm are disposed in the crank chamber 13 and driven by the camshaft 17 that is decelerated from the crankshaft 7, via an intake pushrod 19i and an exhaust pushrod (not shown). It swings and opens and closes the intake valve 12i and the exhaust valve. The intake push rod 19i and the exhaust push rod are disposed so as to pass through the lower side portion of the cylinder block 3.

  In the crank chamber 13, lubricating oil 23 is stored at a constant level that does not reach the lower oil passage 21, and an oil dipper 24 that scatters the oil 23 to generate oil splash is attached to the large end of the connecting rod 9. The

  Further, an upper oil passage 20 passing through the gasket 4 between the cylinder block 3 and the cylinder head 5 and communicating between the crank chamber 13 and the valve operating chamber 14 is provided in the upper and lower portions of the cylinder block 3 and the cylinder head 5. A lower oil passage 21 is provided, and the lower oil passage 21 is disposed between the intake swing push rod 19i and the exhaust push rod.

  The upper oil passage 20 is provided with a one-way valve V that allows a fluid flow from the crank chamber 13 side to the valve operating chamber 14 side but prevents the reverse flow. The one-way valve V is attached to the gasket 4 as follows.

  As shown in FIGS. 3 and 4, the gasket 4 divides the upper oil passage 20 into an upper flow path 20 a on the crank chamber 13 side and a lower flow path 20 b on the valve operating chamber 14 side. The gasket 4 is provided with a valve mounting hole 25 and a plurality of (three in the illustrated example) through-holes 26 that are arranged so as to surround the valve mounting hole 25 and communicate between the upper flow path 20a and the lower flow path 20b. .

  The one-way valve V includes a valve body 28 made of an elastic material such as rubber and a holding member 29 made of a synthetic resin. The valve body 28 includes an elastic umbrella portion 30, a boss portion 31 formed at the center of the elastic umbrella portion 30 and protruding toward the gasket 4, and a flange portion 32 extending from the boss portion 31. The flange portion 32 extends from the boss portion 31 and has a first shaft portion 32a that is sufficiently smaller in diameter than the valve mounting hole 25, and is coaxially connected to the first shaft portion 32a via a huge portion 32c. The second shaft portion 32b is smaller in diameter than the shaft portion 32a. The valve body 28 is disposed so that the flange portion 32 is inserted into the valve mounting hole 25 and the umbrella portion 30 is seated on the upper surface 4a of the gasket 4 facing the lower flow path 20b.

  The holding member 29 has a fitting hole 34 in the center and a positioning claw 35 that protrudes in the axial direction in the same number as the through hole 26 on the outer periphery.

  When the holding member 29 is coupled to the valve body 28, the second shaft portion 32b of the valve body 28 is inserted into the fitting hole 34 and then pulled, and the holding member 29 is moved toward the first shaft portion 32a. Press. Then, since the enormous part 32c is extended and reduced in diameter, the fitting hole 34 of the holding member 29 can pass through the enormous part 32c and be engaged with the first shaft part 32a. Thereafter, when the pulling of the second shaft portion 32b is released, the enormous portion 32c is restored to the original shape of the large diameter and engaged with the back surface of the holding member 29, and the holding member 29 is brought into the fitting position with the first shaft portion 32a. Hold. The holding member 29 fitted to the first shaft portion 32 a holds the gasket 4 in cooperation with the boss portion 31 of the valve body 28.

  At this time, the plurality of positioning claws 35 of the holding member 29 are engaged with the plurality of through holes 26 of the gasket 4 to hold the flange portion 32 in a concentric position with the valve mounting hole 25. As a result, the first shaft portion 32a having a diameter sufficiently smaller than that of the valve mounting hole 25 is placed at a certain distance from the inner peripheral surface of the valve mounting hole 25 over the entire circumference thereof, thereby avoiding contact.

  Although not shown, a breather pipe for discharging blow-by gas to the suction system is connected to the upper part of the valve operating chamber 14.

  Next, the operation of this embodiment will be described.

  When the general-purpose engine E is operating in a normal posture with the installation flange 1 being horizontal, the stored oil 23 in the crank chamber 13 does not reach the lower oil passage 21, and as the crankshaft 7 rotates. A non-oscillating oil dipper 24 strikes and scatters the stored oil 23 to create oil splashes, and the oil splashes lubricate the piston 8 and the connecting rod 9. The oil splashes are divided into the upper oil passage 20 and the lower oil passage 21. , And reaches the valve operating chamber 14 to lubricate the valve operating device 15 as well.

  In particular, the upper oil passage 20 is provided with a one-way valve V that allows the flow of fluid from the crank chamber 13 side to the valve operating chamber 14 side but prevents the reverse flow. Of the pulsating pressure generated in the crank chamber 13 due to the reciprocating motion of the oil, only the positive pressure can pass through the upper oil passage 20, and oil splashes are carried to the valve chamber 14 by riding on the positive pressure. Become.

  That is, of the pulsating pressure generated in the crank chamber 13, when a positive pressure acts on the elastic umbrella portion 30 of the one-way valve V from the through hole 26 of the gasket 4, the elastic umbrella portion 30 is pushed open, and the positive pressure is When the passage 20 is allowed to pass and negative pressure is applied to the elastic umbrella portion 30 from the through hole 26, the elastic umbrella portion 30 is attracted to the gasket 4 side and is seated on the upper surface 4a to close the through hole 26. The negative pressure is prevented from passing through the upper oil passage 20. In this way, only positive pressure passes through the upper oil passage 20.

  Now, assuming that the general-purpose engine E is forced to take a posture in which the inclined cylinder block 3 is further inclined according to the use state of the work implement, the oil 23 in the crank chamber 13 is moved through the lower oil passage 21 to operate the valve. A large amount will flow into the chamber 14. However, if the general-purpose engine E is operated, the positive pressure of the pulsating pressure generated in the crank chamber 13 passes through the upper oil passage 20 by the action of the one-way valve V in the upper oil passage 20 as described above. As a result, the pressure in the valve operating chamber 14 is increased, and the oil 23 flowing into the valve operating chamber 14 can be pushed back to the crank chamber 13 through the lower oil passage 21. Accordingly, it is possible to prevent a decrease in the amount of oil 23 stored in the crank chamber 13, to always generate oil splashes by the oil dipper 24, and to ensure good lubrication of each part of the engine.

  By the way, the gasket 4 interposed between the cylinder block 3 and the cylinder head 5 is provided with a valve mounting hole 25 and through holes 26 communicating with a plurality of upper oil passages 20 arranged so as to surround the valve mounting hole 25. The one-way valve V is provided with an elastic umbrella portion 30 that sits on the upper upper surface 4a of the gasket 4 facing the lower flow path 20b of the upper oil passage 20 and covers the group of through holes 26, and a boss portion of the elastic umbrella portion 30 A valve body 28 formed of a flange portion 32 protruding from 31 and penetrating through the valve mounting hole 25, and a holding member 29 that clamps the gasket 4 in cooperation with the boss portion 31 by being fitted and fixed to the flange portion 32. Therefore, the one-way valve V can be easily installed using the gasket 4, and this one-way valve V can be adopted without significant modification to the conventional general-purpose engine. Improvement cost It can be kept low.

  At this time, the flange portion 32 of the valve body 28 is formed to have a small diameter so that the outer peripheral surface thereof does not contact the inner peripheral surface of the valve mounting hole 25, while the plurality of positioning claws 35 of the holding member 29 are provided with the gasket 4. Since the collar portion 32 is held concentrically with the valve mounting hole 25 by engaging with the through hole 26, the collar portion 32 is placed at a certain distance from the inner peripheral surface of the valve mounting hole 25 over the entire circumference. Therefore, damage due to contact of the flange portion 32 with the sharp inner peripheral edge of the valve mounting hole 25 of the gasket 4 having a small thickness can be prevented and its durability can be maintained. Moreover, since the positioning claw 35 is engaged using the through hole 26 that allows the positive pressure to pass through, it is not necessary to provide a special positioning hole in the gasket 4, which can contribute to simplification of the structure.

  Further, the collar portion 32 extends from the boss portion 31 of the umbrella portion 30 and is fitted to the fitting hole 34 of the holding member 29, and is coaxially connected to the first shaft portion 32a via the enormous portion 32c. The enlarging portion 32c engages with the back surface of the holding member 29 and holds the holding member 29 on the first shaft portion 32a. The second shaft portion 32b has a smaller diameter than the first shaft portion 32a. Thus, when the fitting hole 34 of the holding member 29 is fitted to the first shaft portion 32a, the enormous portion 32c is pulled by pulling the second shaft portion 32b. By reducing the diameter, the fitting hole 34 can easily pass through the enormous portion 32c, and the assemblability of the one-way valve V is good.

  The present invention is not limited to the above embodiment, and various design changes can be made without departing from the scope of the invention. For example, an oil slinger that is driven to rotate by the crankshaft 7 may be used in place of the oil dipper 24 for the generation of oil splashes.

E ... General-purpose engine V ... One-way valve 1 ... Mounting flange 2 ... Crankcase 3 ... Cylinder block 4 ... Gasket 4a ... upper surface 13 of gasket ... crank chamber 14 ... valve operating chamber 20 ... upper oil passage 20a ... upper passage 20b ... lower passage 21 ... lower oil passage 23 .... Oil 24 ... Oil splash generating means (oil dipper)
25... Valve mounting hole 26... Through hole 28... Valve body 29... Holding member 30. Part 32a ... First shaft part 32b ... Second shaft part 32c ... Enormous part 34 ... Fitting hole 35 ... Positioning claw

Claims (4)

A crankcase (2) having a mounting flange (1) at the bottom, a cylinder block (3) extending inclined from one side of the crankcase (2), and a gasket (4) on the end face of the cylinder block (3) A cylinder head (5) joined to each other, and the stored lubricating oil (23) in the crank chamber (13) is scattered in the crank chamber (13) in the crankcase (2) to dissipate the components of the engine. Oil splash generating means (24) for generating oil splashes for lubrication is provided, and a crank chamber (13) and a cylinder head () are provided on the upper and lower parts of the cylinder block (3) and the cylinder head (5). 5) In a general-purpose engine provided with an upper oil passage (20) and a lower oil passage (21) communicating with the valve train chamber (14) in the interior,
The upper oil passage (20) is provided with a one-way valve (V) that allows the flow of fluid from the crank chamber (13) side to the valve operating chamber (14) side but prevents the reverse flow. , When the engine (E) is tilted so that the tilted cylinder block (3) is further tilted, the stored lubricating oil (23) in the crank chamber (13) passes through the lower oil passage (21) to the valve chamber (14). ) Flows into the valve chamber (14) by the positive pressure transmitted from the crank chamber (13) to the valve chamber (14) via the one-way valve (V). ) Is pushed back to the crank chamber (13) through the lower oil passage (21). The general-purpose engine according to claim 1,
The upper oil passage (20) is connected to the upper flow path (20a) and the valve operating chamber (14) on the crank chamber (13) side by a gasket (4) interposed between the cylinder block (3) and the cylinder head (5). ) Side lower flow path (20b), and in the gasket (4), the valve mounting hole (25) and the upper flow path (20a) and the lower flow path ( 20b) are provided with a plurality of through holes (26), and the one-way valve (V) is seated on the upper surface (4a) of the gasket (4) facing the lower flow path (20b). A valve body comprising an elastic umbrella portion (30) covering the group of holes (26) and a flange portion (32) protruding from the boss portion (31) of the elastic umbrella portion (30) and penetrating the valve mounting hole (25). (28) and by fitting and fixing to the flange (32), Part (31) and cooperates with a general-purpose engine which is characterized by being configured out a holding member (29) for clamping the gasket (4). The general-purpose engine according to claim 2,
The flange portion (32) is formed with a small diameter so that the outer peripheral surface thereof does not contact the inner peripheral surface of the valve mounting hole (25), while the holding member (29) has a plurality of the through holes (26). A general-purpose engine provided with a plurality of positioning claws (35) that are engaged with each other and hold the flange (32) in a concentric position with the valve mounting hole (25). The general-purpose engine according to claim 2 or 3,
A first shaft portion (32a) that extends from the boss portion (31) and fits into the fitting hole (34) of the holding member (29), and the first shaft portion (32a) ) And the second shaft portion (32b) having a smaller diameter than the first shaft portion (32a), which is coaxially connected to the holding member (29). A general-purpose engine having a larger diameter than the first shaft portion (32a) so as to be engaged with the back surface and hold the holding member (29) on the first shaft portion (32a).

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